- Modular syntheses of multidentate ligands with variable N-donors: Applications to tri- and tetracopper(i) complexes
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A general method for the preparation of multidentate ligands comprised of a multi-imine platform derived from 1,1,1-tris(aminomethyl)ethane or tris(aminoethyl)amine connected to bi- and tridentate N-donor chelates has been developed. The feasibility of the method has been demonstrated through the synthesis and characterization of a large set of these ligand types. Complexation to Cu(i) was accomplished for several cases, yielding tri- and tetracopper(i) complexes that have been characterized in solution by NMR spectroscopy and conductivity, and in the solid state by elemental analysis, mass spectrometry, and/or X-ray crystallography. These complexes are potentially useful for modeling multicopper protein active sites. The Royal Society of Chemistry.
- Brown, Eric C.,Johnson, Brandon,Palavicini, Sara,Kucera, Benjamin E.,Casella, Luigi,Tolman, William B.
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- Tripodal trisamides based on nicotinic and picolinic acid derivatives
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A number of polydentate arylamide ligands have been prepared by coupling various acyclic tripodal or linear polyamines with derivatives of nicotinic and picolinic acids. Two synthetic procedures were utilized; tris{[(2-hydroxynicotinyl)carbonyl]-2-aminoethyl}amine (H3NICTREN) was prepared by Method A, the HOSu/DCC method, and the other arylamides in this study were prepared by Method B, the CDI method. Method A involved the reaction of N-hydroxysuccinimide with 2-hydroxynicotinic acid (in the presence of dicyclohexylcarbodiimide (DCC) as a dehydrative coupling reagent) to form the succinimide ester, followed by reaction with TREN to yield H3NICTREN. Method B involved reaction of a carboxylic acid (2-hydroxynicotinic, 3-hydroxypicolinic, nicotinic, or picolinic acids) with carbonyldiimidazole (CDI) to form the N-acylimidazolide, followed by reaction with the amine (TREN, TAME, spermidine, or TRPN) to yield the desired arylamide. The X-ray structure of 1,1,1-tris([(3-hydroxypicolinyl)carbonyl]-2-aminomethyl)ethane (H3PICTAME) was determined; crystals of H3PICTAME are monoclinic, a = 10.257(2), b = 15.572(3), c = 15.208(2) A, β = 96.124(15)°, Z = 4, space group P21/a. The structure was solved by direct methods and refined by full-matrix least-squares procedures to R = 0.041 and Rw = 0.038 for 2506 reflections with I ≥gt; 3σ(I). In the solid state, H3PICTAME contains an extensive hydrogen-bonding network, with eight intra- and one intermolecular H-bonds per molecule; the ligand is partially preorganized for metal ion chelation. The acid dissociation constants of H3NICTREN and those of 1,1,1-tris{[(2-hydroxynicotinyl)carbonyl]-2-aminomethyl}ethane (H3NICTAME) have been determined; pKa1 = 11.2 (10.68), pKa2 = 10.7 (10.58), pKa3 = 10.0 (9.71), and pKa4 = 6.25 for H3NICTREN (H3NICTAME); the high phenolic pKa's are consistent with the hydrogen bonding observed in the solid state.
- Hoveyda,Karunaratne, Veranja,Nichols, Christopher J.,Rettig, Steven J.,Stephens, Ashley K. W.,Orvig, Chris
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- Spin Crossover in a Hexaamineiron(II) Complex: Experimental Confirmation of a Computational Prediction
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Single crystal structural analysis of [FeII(tame)2]Cl2?MeOH (tame=1,1,1-tris(aminomethyl)ethane) as a function of temperature reveals a smooth crossover between a high temperature high-spin octahedral d6 state and a low temperature low-spin ground state without change of the symmetry of the crystal structure. The temperature at which the high and low spin states are present in equal proportions is T1/2=140 K. Single crystal, variable-temperature optical spectroscopy of [FeII(tame)2]Cl2?MeOH is consistent with this change in electronic ground state. These experimental results confirm the spin activity predicted for [FeII(tame)2]2+ during its de novo artificial evolution design as a spin-crossover complex [Chem. Inf. Model. 2015, 55, 1844], offering the first experimental validation of a functional transition-metal complex predicted by such in silico molecular design methods. Additional quantum chemical calculations offer, together with the crystal structure analysis, insight into the role of spin-passive structural components. A thermodynamic analysis based on an Ising-like mean field model (Slichter–Drickammer approximation) provides estimates of the enthalpy, entropy and cooperativity of the crossover between the high and low spin states.
- Bernhardt, Paul V.,Bilyj, Jessica K.,Brosius, Victor,Chernyshov, Dmitry,Deeth, Robert J.,Foscato, Marco,Jensen, Vidar R.,Mertes, Nicole,Riley, Mark J.,T?rnroos, Karl W.
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- Design, synthesis and photophysical properties of 8-hydroxyquinoline-functionalized tripodal molecular switch as a highly selective sequential pH sensor in aqueous solution
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The development and photophysical properties of a biomimetic analogue of microbial siderophore from quinolobactin have been described. The putative analogue, 5,5′-(2(((8-hydroxyquinolin-5-yl)methylamino)methyl)2-methylpropane-1,3-diyl)-bis(azanediyl)-bis(methylene)diquinolin-8-ol (TAME5OX), was synthesized with three bidentate 8-hydroxyquinoline (8HQ) groups, connected to a 1,1,1-tris(aminomethyl)ethane framework, and was selected for its potential applications in chemical and biological fields. A combination of absorption and emission spectrophotometry, potentiometry, electrospray mass spectrometry, NMR, IR and theoretical investigation was used to fully characterize TAME5OX. The intense fluorescence from TAME5OX is quenched intermittently under acidic and basic conditions due to the photoinduced intramolecular electron transfer from excited N-pyridyl to hydroxyl moiety of 8HQ units. This renders the ligand an OFF-ON-OFF type of pH-dependent fluorescent sensor. DFT was employed for optimization and evaluation of vibrational modes, excitation and emission properties of the protonated, neutral, deprotonated states of the analogue. Anomalous enhancement observed in the fluorescence spectra of the neutral form of the sensor can be attributed to subtle structural differences from its cationic and anionic forms. Plausible explanations for low fluorescence of the acidic as well as basic form are provided. This journal is
- Akbar, Rifat,Baral, Minati,Kanungo
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- Triamidetriamine bearing macrobicyclic and macrotricyclic ligands: Potential applications in the development of copper-64 radiopharmaceuticals
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A versatile and straightforward synthetic approach is described for the preparation of triamide bearing analogues of sarcophagine hexaazamacrobicyclic cage ligands without the need for a templating metal ion. Reaction of 1,1,1-tris(aminoethyl)ethane (tame) with 3 equiv of 2-chloroacetyl chloride, yields the tris(α-chloroamide) synthetic intermediate 6, which when treated with either 1,1,1-tris(aminoethyl)ethane or 1,4,7-triazacyclononane furnished two novel triamidetriamine cryptand ligands (7 and 8 respectively). The Co(III) and Cu(II) complexes of cryptand 7 were prepared; however, cryptand 8 could not be metalated. The cryptands and the Co(III) complex 9 have been characterized by elemental analysis, 1H and 13C NMR spectroscopy, and X-ray crystallography. These studies confirm that the Co(III) complex 9 adopts an octahedral geometry with three facial deprotonated amido-donors and three facial amine donor groups. The Cu(II) complex 10 was characterized by elemental analysis, single crystal X-ray crystallography, cyclic voltammetry, and UV-visible absorption spectroscopy. In contrast to the Co(III) complex (9), the Cu(II) center adopts a square planar coordination geometry, with two amine and two deprotonated amido donor groups. Compound 10 exhibited a quasi-reversible, one-electron oxidation, which is assigned to the Cu2+/3+ redox couple. These cryptands represent interesting ligands for radiopharmaceutical applications, and 7 has been labeled with 64Cu to give 64Cu-10. This complex showed good stability when subjected to L-cysteine challenge whereas low levels of decomplexation were evident in the presence of L-histidine.
- Tan, Kel Vin,Pellegrini, Paul A.,Skelton, Brian W.,Hogan, Conor F.,Greguric, Ivan,Barnard, Peter J.
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- Cation-Exchange Chromatography and Selective Complexation in hte Isolation of Branched Acyclic Polyamines: Syntheses of Ethylidenetris(methanamine) , 2,2-Bis(aminomethyl)propan-1-ol , 4,4',4''-Ethylidenetris(3-azabutan-1-amine) and...
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Large-scale syntheses of ethylidynetris(methanamine) (tame), 2,2-bis(aminomethyl)propan-1-ol (hmmp), 4,4'-4'-ethylidynetris(3-azabutan-1-amine) (sen) and 5,5'-5'-ethylidynetris(4-azapentan-1-amine) (stn) are described.The pure hydrochloride salts of tame,
- Geue, Rodney J.,Searle, Graeme H.
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- Peptide-based compounds
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The invention relates to new peptide-based compounds for use as diagnostic imaging agents or as therapeutic agents wherein the agents comprise a targeting vector which binds to receptors associated with integrin receptors.
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- Process for the preparation of amines
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A single-stage process is described for the preparation of primary aliphatic polyamines of the formula in which R1and R2independently of one another are hydrogen, methyl, ethyl or aminomethyl, by reaction of polyalcohols on a Co/Ni catalyst with supercritical ammonia in the presence of hydrogen.
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- Synthesis of the smallest tris-(catecholamide) siderophore analogue
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The tris-(catecholamide) (H6L) (8) was synthesised in six steps and characterized. This is the smallest analogue of naturally occurring siderophores structurally related to an approved enterobactin and protochelin model, known up to now.
- Cheraiti,Brik,Kunesch,Gaudemer
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p. 149 - 152
(2007/10/03)
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- Synthesis and electrochemical study of a new chiral tris- catecholamide analogue of enterobactin
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The comparison of siderophore complex redox potentials with those of physiological reductants may aid in the clarification of the mechanism of iron metabolism. In this paper, a new chiral tris-catecholamide compound N,N',N''-tris-(2,3-dihydroxybenzoyl)-1,
- Cheraiti,Brik,Gaudemer,Kunesh
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p. 781 - 786
(2007/10/03)
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